Firebird 2.1 Language Reference Update

Context variables
Description: OLD contains the existing version of a database record just before a deletion or update. Starting
with Firebird 2.0 it is read-only.
Type: Data row
Note
Available in: PSQL
Added in: 1.5
Changed in: 2.0
In multi-action triggers – introduced in Firebird 1.5 – OLD is always available. But if the trigger is fired by
an INSERT, there is obviously no pre-existing version of the record. In that situation, reading from OLD will
always return NULL; writing to it will cause a runtime exception.
ROW_COUNT
Description: The ROW_COUNT context variable contains the number of rows affected by the most recent DML
statement (INSERT, UPDATE, DELETE, SELECT or FETCH) in the current trigger, stored procedure or executable
block.
Type: INTEGER
Example:
update Figures set Number = 0 where id = :id;
if (row_count = 0) then
insert into Figures (id, Number) values (:id, 0);
Behaviour with SELECT and FETCH:
• After a singleton SELECT, ROW_COUNT is 1 if a data row was retrieved and 0 otherwise.
• In a FOR SELECT loop, ROW_COUNT is incremented with every iteration (starting at 0 before the first).
• After a FETCH from a cursor, ROW_COUNT is 1 if a data row was retrieved and 0 otherwise. Fetching more
records from the same cursor does not increment ROW_COUNT beyond 1.
• In Firebird 1.5.x, ROW_COUNT is 0 after any type of SELECT statement.
Note
ROW_COUNT cannot be used to determine the number of rows affected by an EXECUTE STATEMENT or EXE-
CUTE PROCEDURE command.
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